/* eslint-disable no-undef */
/*!
 * Signature Pad v2.1.1
 * https://github.com/szimek/signature_pad
 *
 * Copyright 2017 Szymon Nowak
 * Released under the MIT license
 *
 * The main idea and some parts of the code (e.g. drawing variable width Bézier curve) are taken from:
 * http://corner.squareup.com/2012/07/smoother-signatures.html
 *
 * Implementation of interpolation using cubic Bézier curves is taken from:
 * http://benknowscode.wordpress.com/2012/09/14/path-interpolation-using-cubic-bezier-and-control-point-estimation-in-javascript
 *
 * Algorithm for approximated length of a Bézier curve is taken from:
 * http://www.lemoda.net/maths/bezier-length/index.html
 *
 */

(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
    typeof define === 'function' && define.amd ? define(factory) :
      global.SignaturePad = factory();
}(this, function () {
  'use strict';

  function Point(x, y, time) {
    this.x = x;
    this.y = y;
    this.time = time || new Date().getTime();
  }

  Point.prototype.velocityFrom = function (start) {
    return this.time !== start.time ? this.distanceTo(start) / (this.time - start.time) : 1;
  };

  Point.prototype.distanceTo = function (start) {
    return Math.sqrt(Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2));
  };

  function Bezier(startPoint, control1, control2, endPoint) {
    this.startPoint = startPoint;
    this.control1 = control1;
    this.control2 = control2;
    this.endPoint = endPoint;
  }

  // Returns approximated length.
  Bezier.prototype.length = function () {
    var steps = 10;
    var length = 0;
    var px = void 0;
    var py = void 0;

    for (var i = 0; i <= steps; i += 1) {
      var t = i / steps;
      var cx = this._point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
      var cy = this._point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
      if (i > 0) {
        var xdiff = cx - px;
        var ydiff = cy - py;
        length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
      }
      px = cx;
      py = cy;
    }

    return length;
  };

  /* eslint-disable no-multi-spaces, space-in-parens */
  Bezier.prototype._point = function (t, start, c1, c2, end) {
    return start * (1.0 - t) * (1.0 - t) * (1.0 - t) + 3.0 * c1 * (1.0 - t) * (1.0 - t) * t + 3.0 * c2 * (1.0 - t) * t * t + end * t * t * t;
  };

  /* eslint-disable */

  // http://stackoverflow.com/a/27078401/815507
  function throttle(func, wait, options) {
    var context, args, result;
    var timeout = null;
    var previous = 0;
    if (!options) options = {};
    var later = function later() {
      previous = options.leading === false ? 0 : Date.now();
      timeout = null;
      result = func.apply(context, args);
      if (!timeout) context = args = null;
    };
    return function () {
      var now = Date.now();
      if (!previous && options.leading === false) previous = now;
      var remaining = wait - (now - previous);
      context = this;
      args = arguments;
      if (remaining <= 0 || remaining > wait) {
        if (timeout) {
          clearTimeout(timeout);
          timeout = null;
        }
        previous = now;
        result = func.apply(context, args);
        if (!timeout) context = args = null;
      } else if (!timeout && options.trailing !== false) {
        timeout = setTimeout(later, remaining);
      }
      return result;
    };
  }

  function SignaturePad(canvas, options) {
    var self = this;
    var opts = options || {};

    this.velocityFilterWeight = opts.velocityFilterWeight || 0.7;
    this.minWidth = opts.minWidth || 0.5;
    this.maxWidth = opts.maxWidth || 2.5;
    this.throttle = 'throttle' in opts ? opts.throttle : 16; // in miliseconds

    if (this.throttle) {
      this._strokeMoveUpdate = throttle(SignaturePad.prototype._strokeUpdate, this.throttle);
    } else {
      this._strokeMoveUpdate = SignaturePad.prototype._strokeUpdate;
    }

    this.dotSize = opts.dotSize || function () {
      return (this.minWidth + this.maxWidth) / 2;
    };
    this.penColor = opts.penColor || 'black';
    this.backgroundColor = opts.backgroundColor || 'rgba(0,0,0,0)';
    this.onBegin = opts.onBegin;
    this.onEnd = opts.onEnd;

    this._canvas = canvas;
    this._ctx = canvas.getContext('2d');
    this.clear();

    // We need add these inline so they are available to unbind while still having
    // access to 'self' we could use _.bind but it's not worth adding a dependency.
    this._handleMouseDown = function (event) {
      if (event.which === 1) {
        self._mouseButtonDown = true;
        self._strokeBegin(event);
      }
    };

    this._handleMouseMove = function (event) {
      if (self._mouseButtonDown) {
        self._strokeMoveUpdate(event);
      }
    };

    this._handleMouseUp = function (event) {
      if (event.which === 1 && self._mouseButtonDown) {
        self._mouseButtonDown = false;
        self._strokeEnd(event);
      }
    };

    this._handleTouchStart = function (event) {
      if (event.targetTouches.length === 1) {
        var touch = event.changedTouches[0];
        self._strokeBegin(touch);
      }
    };

    this._handleTouchMove = function (event) {
      // Prevent scrolling.
      event.preventDefault();

      var touch = event.targetTouches[0];
      self._strokeMoveUpdate(touch);
    };

    this._handleTouchEnd = function (event) {
      var wasCanvasTouched = event.target === self._canvas;
      if (wasCanvasTouched) {
        event.preventDefault();
        self._strokeEnd(event);
      }
    };

    // Enable mouse and touch event handlers
    this.on();
  }

  // Public methods
  SignaturePad.prototype.clear = function () {
    var ctx = this._ctx;
    var canvas = this._canvas;

    ctx.fillStyle = this.backgroundColor;
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    this._data = [];
    this._reset();
    this._isEmpty = true;
  };

  SignaturePad.prototype.fromDataURL = function (dataUrl) {
    var _this = this;

    var image = new Image();
    var ratio = window.devicePixelRatio || 1;
    var width = this._canvas.width / ratio;
    var height = this._canvas.height / ratio;

    this._reset();
    image.src = dataUrl;
    image.onload = function () {
      _this._ctx.drawImage(image, 0, 0, width, height);
    };
    this._isEmpty = false;
  };


  function dataURLtoBlob(dataurl) {
    var arr = dataurl.split(','),
      mime = arr[0].match(/:(.*?);/)[1],
      bstr = atob(arr[1]),
      n = bstr.length,
      u8arr = new Uint8Array(n);
    while (n--) {
      u8arr[n] = bstr.charCodeAt(n);
    }
    return new Blob([u8arr], { type: mime });
  };
  SignaturePad.prototype.toDataURL = function (type) {
    var _canvas;

    switch (type) {
      case 'image/svg+xml':
        return this._toSVG();
      default:
        for (var _len = arguments.length, options = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
          options[_key - 1] = arguments[_key];
        }

        var d = Math.floor(new Date().getTime() / 16);
        var r = (d + Math.random() * 16) % 16 | 0;
        var fileName = d + r + '.png'

        let base64 = (_canvas = this._canvas).toDataURL.apply(_canvas, [type].concat(options));
        var blob = dataURLtoBlob(base64);
        var file = new File([blob], fileName)
        return { file, base64 }
    }
  };

  SignaturePad.prototype.on = function () {
    this._handleMouseEvents();
    this._handleTouchEvents();
  };

  SignaturePad.prototype.off = function () {
    this._canvas.removeEventListener('mousedown', this._handleMouseDown);
    this._canvas.removeEventListener('mousemove', this._handleMouseMove);
    document.removeEventListener('mouseup', this._handleMouseUp);

    this._canvas.removeEventListener('touchstart', this._handleTouchStart);
    this._canvas.removeEventListener('touchmove', this._handleTouchMove);
    this._canvas.removeEventListener('touchend', this._handleTouchEnd);
  };

  SignaturePad.prototype.isEmpty = function () {
    return this._isEmpty;
  };

  // Private methods
  SignaturePad.prototype._strokeBegin = function (event) {
    this._data.push([]);
    this._reset();
    this._strokeUpdate(event);

    if (typeof this.onBegin === 'function') {
      this.onBegin(event);
    }
  };

  SignaturePad.prototype._strokeUpdate = function (event) {
    var x = event.clientX;
    var y = event.clientY;

    var point = this._createPoint(x, y);

    var _addPoint = this._addPoint(point),
      curve = _addPoint.curve,
      widths = _addPoint.widths;

    if (curve && widths) {
      this._drawCurve(curve, widths.start, widths.end);
    }

    this._data[this._data.length - 1].push({
      x: point.x,
      y: point.y,
      time: point.time
    });
  };

  SignaturePad.prototype._strokeEnd = function (event) {
    var canDrawCurve = this.points.length > 2;
    var point = this.points[0];

    if (!canDrawCurve && point) {
      this._drawDot(point);
    }

    if (typeof this.onEnd === 'function') {
      this.onEnd(event);
    }
  };

  SignaturePad.prototype._handleMouseEvents = function () {
    this._mouseButtonDown = false;

    this._canvas.addEventListener('mousedown', this._handleMouseDown);
    this._canvas.addEventListener('mousemove', this._handleMouseMove);
    document.addEventListener('mouseup', this._handleMouseUp);
  };

  SignaturePad.prototype._handleTouchEvents = function () {
    // Pass touch events to canvas element on mobile IE11 and Edge.
    this._canvas.style.msTouchAction = 'none';
    this._canvas.style.touchAction = 'none';

    this._canvas.addEventListener('touchstart', this._handleTouchStart);
    this._canvas.addEventListener('touchmove', this._handleTouchMove);
    this._canvas.addEventListener('touchend', this._handleTouchEnd);
  };

  SignaturePad.prototype._reset = function () {
    this.points = [];
    this._lastVelocity = 0;
    this._lastWidth = (this.minWidth + this.maxWidth) / 2;
    this._ctx.fillStyle = this.penColor;
  };

  SignaturePad.prototype._createPoint = function (x, y, time) {
    var rect = this._canvas.getBoundingClientRect();

    return new Point(x - rect.left, y - rect.top, time || new Date().getTime());
  };

  SignaturePad.prototype._addPoint = function (point) {
    var points = this.points;
    var tmp = void 0;

    points.push(point);

    if (points.length > 2) {
      // To reduce the initial lag make it work with 3 points
      // by copying the first point to the beginning.
      if (points.length === 3) points.unshift(points[0]);

      tmp = this._calculateCurveControlPoints(points[0], points[1], points[2]);
      var c2 = tmp.c2;
      tmp = this._calculateCurveControlPoints(points[1], points[2], points[3]);
      var c3 = tmp.c1;
      var curve = new Bezier(points[1], c2, c3, points[2]);
      var widths = this._calculateCurveWidths(curve);

      // Remove the first element from the list,
      // so that we always have no more than 4 points in points array.
      points.shift();

      return { curve: curve, widths: widths };
    }

    return {};
  };

  SignaturePad.prototype._calculateCurveControlPoints = function (s1, s2, s3) {
    var dx1 = s1.x - s2.x;
    var dy1 = s1.y - s2.y;
    var dx2 = s2.x - s3.x;
    var dy2 = s2.y - s3.y;

    var m1 = { x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0 };
    var m2 = { x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0 };

    var l1 = Math.sqrt(dx1 * dx1 + dy1 * dy1);
    var l2 = Math.sqrt(dx2 * dx2 + dy2 * dy2);

    var dxm = m1.x - m2.x;
    var dym = m1.y - m2.y;

    var k = l2 / (l1 + l2);
    var cm = { x: m2.x + dxm * k, y: m2.y + dym * k };

    var tx = s2.x - cm.x;
    var ty = s2.y - cm.y;

    return {
      c1: new Point(m1.x + tx, m1.y + ty),
      c2: new Point(m2.x + tx, m2.y + ty)
    };
  };

  SignaturePad.prototype._calculateCurveWidths = function (curve) {
    var startPoint = curve.startPoint;
    var endPoint = curve.endPoint;
    var widths = { start: null, end: null };

    var velocity = this.velocityFilterWeight * endPoint.velocityFrom(startPoint) + (1 - this.velocityFilterWeight) * this._lastVelocity;

    var newWidth = this._strokeWidth(velocity);

    widths.start = this._lastWidth;
    widths.end = newWidth;

    this._lastVelocity = velocity;
    this._lastWidth = newWidth;

    return widths;
  };

  SignaturePad.prototype._strokeWidth = function (velocity) {
    return Math.max(this.maxWidth / (velocity + 1), this.minWidth);
  };

  SignaturePad.prototype._drawPoint = function (x, y, size) {
    var ctx = this._ctx;

    ctx.moveTo(x, y);
    ctx.arc(x, y, size, 0, 2 * Math.PI, false);
    this._isEmpty = false;
  };

  SignaturePad.prototype._drawCurve = function (curve, startWidth, endWidth) {
    var ctx = this._ctx;
    var widthDelta = endWidth - startWidth;
    var drawSteps = Math.floor(curve.length());

    ctx.beginPath();

    for (var i = 0; i < drawSteps; i += 1) {
      // Calculate the Bezier (x, y) coordinate for this step.
      var t = i / drawSteps;
      var tt = t * t;
      var ttt = tt * t;
      var u = 1 - t;
      var uu = u * u;
      var uuu = uu * u;

      var x = uuu * curve.startPoint.x;
      x += 3 * uu * t * curve.control1.x;
      x += 3 * u * tt * curve.control2.x;
      x += ttt * curve.endPoint.x;

      var y = uuu * curve.startPoint.y;
      y += 3 * uu * t * curve.control1.y;
      y += 3 * u * tt * curve.control2.y;
      y += ttt * curve.endPoint.y;

      var width = startWidth + ttt * widthDelta;
      this._drawPoint(x, y, width);
    }

    ctx.closePath();
    ctx.fill();
  };

  SignaturePad.prototype._drawDot = function (point) {
    var ctx = this._ctx;
    var width = typeof this.dotSize === 'function' ? this.dotSize() : this.dotSize;

    ctx.beginPath();
    this._drawPoint(point.x, point.y, width);
    ctx.closePath();
    ctx.fill();
  };

  SignaturePad.prototype._fromData = function (pointGroups, drawCurve, drawDot) {
    for (var i = 0; i < pointGroups.length; i += 1) {
      var group = pointGroups[i];

      if (group.length > 1) {
        for (var j = 0; j < group.length; j += 1) {
          var rawPoint = group[j];
          var point = new Point(rawPoint.x, rawPoint.y, rawPoint.time);

          if (j === 0) {
            // First point in a group. Nothing to draw yet.
            this._reset();
            this._addPoint(point);
          } else if (j !== group.length - 1) {
            // Middle point in a group.
            var _addPoint2 = this._addPoint(point),
              curve = _addPoint2.curve,
              widths = _addPoint2.widths;

            if (curve && widths) {
              drawCurve(curve, widths);
            }
          } else {
            // Last point in a group. Do nothing.
          }
        }
      } else {
        this._reset();
        var _rawPoint = group[0];
        drawDot(_rawPoint);
      }
    }
  };

  SignaturePad.prototype._toSVG = function () {
    var _this2 = this;

    var pointGroups = this._data;
    var canvas = this._canvas;
    var ratio = Math.max(window.devicePixelRatio || 1, 1);
    var minX = 0;
    var minY = 0;
    var maxX = canvas.width / ratio;
    var maxY = canvas.height / ratio;
    var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');

    svg.setAttributeNS(null, 'width', canvas.width);
    svg.setAttributeNS(null, 'height', canvas.height);

    this._fromData(pointGroups, function (curve, widths) {
      var path = document.createElement('path');

      // Need to check curve for NaN values, these pop up when drawing
      // lines on the canvas that are not continuous. E.g. Sharp corners
      // or stopping mid-stroke and than continuing without lifting mouse.
      if (!isNaN(curve.control1.x) && !isNaN(curve.control1.y) && !isNaN(curve.control2.x) && !isNaN(curve.control2.y)) {
        var attr = 'M ' + curve.startPoint.x.toFixed(3) + ',' + curve.startPoint.y.toFixed(3) + ' ' + ('C ' + curve.control1.x.toFixed(3) + ',' + curve.control1.y.toFixed(3) + ' ') + (curve.control2.x.toFixed(3) + ',' + curve.control2.y.toFixed(3) + ' ') + (curve.endPoint.x.toFixed(3) + ',' + curve.endPoint.y.toFixed(3));

        path.setAttribute('d', attr);
        path.setAttribute('stroke-width', (widths.end * 2.25).toFixed(3));
        path.setAttribute('stroke', _this2.penColor);
        path.setAttribute('fill', 'none');
        path.setAttribute('stroke-linecap', 'round');

        svg.appendChild(path);
      }
    }, function (rawPoint) {
      var circle = document.createElement('circle');
      var dotSize = typeof _this2.dotSize === 'function' ? _this2.dotSize() : _this2.dotSize;
      circle.setAttribute('r', dotSize);
      circle.setAttribute('cx', rawPoint.x);
      circle.setAttribute('cy', rawPoint.y);
      circle.setAttribute('fill', _this2.penColor);

      svg.appendChild(circle);
    });

    var prefix = 'data:image/svg+xml;base64,';
    var header = '<svg' + ' xmlns="http://www.w3.org/2000/svg"' + ' xmlns:xlink="http://www.w3.org/1999/xlink"' + (' viewBox="' + minX + ' ' + minY + ' ' + maxX + ' ' + maxY + '"') + (' width="' + maxX + '"') + (' height="' + maxY + '"') + '>';
    var body = svg.innerHTML;

    // IE hack for missing innerHTML property on SVGElement
    if (body === undefined) {
      var dummy = document.createElement('dummy');
      var nodes = svg.childNodes;
      dummy.innerHTML = '';

      for (var i = 0; i < nodes.length; i += 1) {
        dummy.appendChild(nodes[i].cloneNode(true));
      }

      body = dummy.innerHTML;
    }

    var footer = '</svg>';
    var data = header + body + footer;

    return prefix + btoa(data);
  };

  SignaturePad.prototype.fromData = function (pointGroups) {
    var _this3 = this;

    this.clear();

    this._fromData(pointGroups, function (curve, widths) {
      return _this3._drawCurve(curve, widths.start, widths.end);
    }, function (rawPoint) {
      return _this3._drawDot(rawPoint);
    });
  };

  SignaturePad.prototype.toData = function () {
    return this._data;
  };

  return SignaturePad;

}));
